Micrometer and gage attachment



F. M. JOHNSON.

MICROMETER AND GAGE ATTACHMENT.

APPLICATION FILED OCT. 11. l9l7.

Patented Jan. :20, 1920.

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MICROMETER AND GAGE ATTACHMENT.

APPLICATION FILED OCT. 11, m7.

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Patented J an. 20, 1920. I

FRANK MAURICE JOHNSON, OF DENVER, COLORADO.

MICROMETER AND GAGE ATTACHMENT.

Specification of Letters Patent.

Patented Jan. 20, 1920.

Application filed October 11, 1917. Serial No. 195,999.

To all whom it may concern:

Be it known that I, n RAIIK ll IAURICE JOHN- SON, a citizen of theUnited States, residing at Denver, in the county of Denver and State ofColorado, have invented a new and useful Micrometer and Gage Attachment,of which the following is a specification.

The subject of this invention is an attachment for micrometers andsimilar gages, and the objects of the invention are, first, to provide amicrometer which may be accurately used in the hands of a novice,second, to provide a micrometer which will accurately indicate minutevariations from a correct setting, third, to provide means for lockingthe micrometer at a desired reading, fourth, to provide an attachmentwhich may be applied to the usual micrometer or gage with a minimum ofchange in the structure thereof, fifth, to provide a simple andeflicient micrometer attachment.

lVith the foregoing and other objects in view, which will appear as thedescription proceeds the invention resides in the combination andarrangement of parts and in the details of construction hereinafterdescribed and claimed, it being understood that changes in the preciseembodiment of the invention herein disclosed can be made within thescope of what is claimed, without departing from the spirit of theinvention.

Practical embodiments of the invention are shown in the accompanyingdrawings, wherein Figure 1 is a central longitudinal section of theattachment;

Fig. 2 is a section on the line :22, Fig. 1;

Fig. 3 is a view in elevation of the attaching lug, a fragment of themicrometer frame being shown;

Fig. 4 is a cross section on the line 1-:t of Fig. 1;

Fig. 5 is a section on the line 55 of Fig. 1;

F ig. 6 is a view in elevation of a modified form of the device;

Fig. 7 is a longitudinal section of the same with the dial and itscasing broken away.

Referring to the drawings by numerals of reference An arm of the yoke ofa micrometer frame is indicated at 1 and the end of this arm is reducedto form the tongue 2. An attaching lug 3 is bifurcated to straddlethetongue 2 to which it may be secured by a screw 1 and pins 5 or in anyother suitable and convenient manner.

The attaching lug is formed with a barrel 6 for the reception of thereduced end 7 of the attachment.

The attachment consists of a preferably cylindrical tube 8 of which thereduced end 7, heretofore mentioned, forms a part. The reduced end 7extends through the barrel 6 and has its projecting end threaded for thereception of a clamping nut 9, as seen most clearly in Fig. 1.

The reduced end 7 and a portion of the main body of the cylinder 8adjacent the reduced end is formed with a reduced bore in which slides ashaft 10 to the outer end of which is securec. an anvil 11. The bead ofthis anvil is formed with a rounded annular flange, as shown, to causethe device to ride more easily onto the work or object to be measured.

The inner end of the shaft 10 is bored and tapped to receive the reducedand threaded end 12 of a shaft 13 which is preferably provided at itsouter end with a knurled head 14.

A sleeve 15 slides in the cylinder 8 and is interiorly threaded toreceive the threaded portion 16 of the shaft 13. This sleeve ispreferably split, as indicated in Fig. 4, and is bound by a screw 17.The purpose of this structure is to compensate for wear and keep theparts in proper adjustment. The screw 17 is formed to project beyond thesleeve at each end and enter slots 18 which are provided in the cylinder8. The movement of the sleeve within the cylinder is limited by thisscrew and the slots within which the screw projects. As will be apparentfrom Fig. 1, the sleeve 15 normally abuts the wall 19 which is formed bythe thickening of the walls of the cylinder at that part containing thereduced bore.

The free end of the cylinder 8 is threaded to receive a tensioning screw20 which is preferably formed with a knurled head 21. The tensioningscrew 20 is longitudinally bored to receive the shaft 13 with a slidingfit, and the screw is operated to tension a coiled spring 22 whichsurrounds the shaft 13 and is confined between the inner end of thescrew 20 and the opposed end of the sleeve 15.

At a median point the cylinder 8 is tapped transversely to receive alocking screw 23. The inner end of the screw 23 is provided with alongitudinal socket in which turns the stem 24 of a contact point. Thehead 25 of the contact point enters a cut out formed at one point on theshaft 10. A lever 26 is threaded onto the outer end of the screw 23 onwhich it is bound by a lock nut 27.

This structure permits the anvil to be locked against motion so as topreserve the measurement which has been taken, if desired.

Hung from the cylinder 8, to which it is secured in any suitable manneris a casing 28 which houses the indicating mechanism of the device.Within this casing a plate 29 is adjustably mounted. One end of thisplate is pivotally secured by a pin 30 to the cylinder 8 while adjacentthe other end the plate has pivoted connection with a screw 31 whichpasses through a block 32 in which it is adjustable by the lock nuts 33.The plate is formed with a longitudinal slot 34 in which is adjustablysecured a pivot pin 35 which is clamped in position upon said plate bythe thumb nut 36.

A lever 37 is pivotally secured at one end, to the sleeve 15, which isprovided with an aperture for the reception of such end. This lever isprovided with a longitudinal slot.

38 through which projects the adjustable journaling pin 35.

The free end of of the lever 37 is angled as shown at 39 and to thisangled end is pivotally secured a yoke 40 the inner face or edge of onearm of which is formed to provide a rack 41.

The rack 41 engages a pinion 42 which is suitably journaled in thecasing 28 and which is integral with or otherwise connected to asegmental gear 43. The segmental gear 43 meshes with apinion 44 which isrigid on the same shaft with or integral with a gear wheel 45. The shafton which the pinion 44 and gear wheel 45 are mounted is as will bereadily understood, journaled in the casing 28. A pinion 46, which isrigid on the pointer shaft, meshes with the gear wheel 45.

A hair spring 47 surrounds the pointer shaft and has one end secured tothe pointer shaft and the other end secured to the casing 28. Thisspring prevents back lash of the pointer and serves to bring the pointerquickly to rest at the proper point on the dial. A dial 48 is providedon the front of the casing 28 and a pointer 49 which is mounted on thepointer shaft, oscillates over the dial.

While the dial may be divided to suit the convenience of the maker andthe work to which the micrometer is to be put, the one herein shown isdivided into two-hundred equal graduations, each group of fivegraduations being suitably indicated, and each ten such groups of fivebeing further indicated, as will be evident from Fig. 6.

From the foregoing it will be evident that, with a micrometer, the screwof which advances the ten-thousandth of an inch for a revolution of thescrew, the mechanism of the attachment is set so that one revolution ofthe screw will advance the pointer 49 through ten groups of five, orthrough fifty divisions, and an advance of the pointer through onedivision will represent an advance of the micrometer screw of onefiftythousandth of an inch. In the foregoing it is assumed that themicrometer screw is so situated as to move the anvil, as by having workplaced between its contact point and the anvil, or the contact pointbrought against the anvil.

lVhile the division between every tenth group of five divisions has beenindicated herein by a zero, it is to be understood that any desiredmethod of indicating these points may be resorted to.

In the modification shown in Figs. 6 and 7, the attachment embodies thesame principles as those forming the basis of the structure justdescribed. There are, however, differences in structural details whichwill now be described.

The cylinder 8 is of uniform diameter and bore throughout and throughthis cylinder extends the shaft 13 which is formed with a head 50. Theend of this head is apertured and threaded to receive an adjusting screw51 which is bound in adjusted position by a lock nut 52.

A collar 53 is rigid on the shaft 13 and is provided with extending lugs54 which enter grooves 55 formed in the cylinder 8 and serve to limitthe movement of the shaft 13.

A coiled spring 22 surrounds the shaft 13 and abuts the collar 53 andthe adjusting nut 20" which is threaded in one end of the cylinder 8.

The anvil 56 of the micrometer 1 is apertured, as shown in Fig. 7, toslidably receive the end of a screw 57 which is threaded into the crosshead 58 of a strap 59. The screw 57 is locked in any adjusted positionby a lock nut 60 with its head normally 'contacting the protruding endof the adjusting screw 51.

The strap 59 embraces the arm of the micrometer 1, and is slidablethereon, and carries a cap 61 which fits over the head of the anvil 56.

A lug strap 62 extends from the casing 28 and embraces the arm of themicrometer 1 and is clamped in place about the arm by the screws 63.

As will be readily apparent, other forms of gearing may be used fortransferring movement to the indicator needle 49 or 49 and other formsof adjustment may be resorted to. Changes in the details of constructionand methods of attachment may also be resorted to when the attachment isto be used on a snap gage, or when it is to be applied to a micrometerintended for interior measurements.

In practice the device is used as fol lows The shaft 13 is adjusted tobring the pointer 19 on the zero between the .003 and .001 (for theposition see the dial, Fig. 6, and the position of the needle i9), andtheipivot 35 and plate 29 so adjusted that movement of the sleeve 15through a distance of four thousandths of an inch will cause the needleto make one revolution.

The distances herein given are selected from one form of device as hereshown but it is understood that the ratio between the movement of thesleeve and hand may be changed as also the amount of movement of whichthe sleeve is capable. This will depend entirely on the character ofwork the micrometer is designed to measure.

IVith the parts so adjusted, the article or work to be measured isbrought between the arms of the micrometer yoke, as usual, and thesleeve of the micrometer turned in the usual way until the indicatorneedle is brought to rest upon the zero between plus and minus on thedial, that is the zero at the top of the dial. The reading on themicrometer will then give the eXact dimension of the part measured.

WVhen reducing a piece of Work to a required size, the micrometer may beset to that size, and the work inserted, from time to time between theend of the micrometer screw and the anvil, when the indicator 4:9 or 19,as the case may be, will tell at a glanceif the work is down to therequired size. If the work is still over size, the pointer will beforced to the right of the zero mark at the top of the dial and, readingfrom such zero mark, will indicate the amount which the work is still tobe reduced. If the indicator fails to reach the zero mark at the top ofthe dial, it will indicate that the work has been too much reduced andis undersize.

In using the modified form shown in Figs. 6 and 7, the parts areadjusted so that the end of the screw 51 will contact the head of thescrew 57 and hold the cap 61 of the strap 59 out of contact with theanvil head. Movement of the work to be measured against the cap 61 willthen cause the shaft 13 and its head to be moved rectilinearly, whichwill actuate the mechanism of the attachment and indicate such movementon the dial in the manner heretofore described in relation to thepreferred form.

Having thus described the invention what is claimed as new and sought byLetters Patent, is

1. A micrometer attachment, comprising a movable anvil, a tubularmember, an element sliding in the tubular member and actuated bymovement of the anvil, resilient means for holding the sliding elementin normal position, a lever secured to the sliding element, anadjustable fulcrum for the lever, and means controlled by the lever forindicating the movement of the anvil.

2. A micrometer attachment, comprising a movable anvil, a tubularmember, an element sliding in the tubular member and actuated bymovement of the anvil, means for holding the sliding element in normalposition, a plate secured to the tubular member, means for adjusting theplate, a lever pivoted to the sliding member and fulcrumed on the plate,and means controlled by the lever for indicating the movement of! theanvil.

In testimony that I claim the foregoing as my own I have hereto aflixedmy signature in the presence of two witnesses.

FRANK MAURICE JOHNSON.

Witnesses:

ROBERT BELL, THOS. T. MARTIN.

